1. Field of the Invention
The present invention relates generally to control apparatus and more particularly to clutch controlling apparatus having a fluid pressure clutch control circuit for deactivating a clutch within a vehicle transmission which is interdependently associated with a brake pedal within a vehicle, especially an industrial vehicle having a power shift mechanism.
2. Description of the Prior Art
Heretofore, regulator valves used in clutch fluid pressure control circuits have been formed for the purpose of maintaining a predetermined pressure, but have not been considered to relate to an inching action. Accordingly, the inching valve of such circuits usually have two orifice cylindrical sections which are respectively, separated in the axial direction. One of the orifice cylindrical sections controls the fluid pressure from the fluid pressure source to the clutch and the other orifice cylindrical section controls the pressure exhausted to a drain port, both of the orifice cylindrical sections being related to each other so as to provide the fluid pressure, required for the inching function, to the clutch. In order to achieve such relativity however, there have been difficulties in the design of the circuit.